The main advantage of having multiple SnapInfo directories is the support of NTFS hard links for archiving transaction logs, which helps to free the system resources and disk space. The use of multiple SnapInfo directories also minimizes your exposure to the loss of backups if a SnapInfo directory is lost.
Multiple SnapInfo directories enable copy-less transaction log archiving with the use of NTFS hard links. The transaction logs must reside on the same NTFS volume as the SnapInfo directory. If you configure an environment with a single SnapInfo directory for all Storage Groups, SnapManager can still use NTFS hard links to archive transaction logs.
In most SnapManager environments, however, the transaction log files are stored on multiple LUNs in multiple volumes. In this configuration, the use of NTFS hard links to archive transaction logs requires a separate SnapInfo directory for each Storage Group. Each SnapInfo directory should be placed on the same NTFS volume as the transaction logs for that Storage Group.